We plan to use red cell membranes as a model for the biosynthesis of membrane proteins. Specifically, we will study the process by which two membrane proteins, spectrin and band 3, are synthesized and incorporated into the erythrocyte membrane. To do this, we have developed antisera capable of specifically precipitating these two proteins. We plan to study the synthesis of these membrane proteins in cell free systems prepared from bone marrow cells of anemic rabbits. We hope to learn whether these proteins, examples of extrinsic and intrinsic membrane proteins, are synthesized in the same part of the cell and whether they are incorporated into the cell surface membrane by similar or different mechanisms. These studies may lead to a better understanding of the mechanisms by which cell surface structures are synthesized and incorporated into the cellular membranes.